On Wed, Oct 21, 2020 at 03:41:00PM -0400, Devin Heitmueller wrote:
> On Wed, Oct 21, 2020 at 9:48 AM <lance.lmw...@gmail.com> wrote:
> >
> > From: Limin Wang <lance.lmw...@gmail.com>
> >
> > now first_pts assume dts will start from zero, if it's not true(copyts is
> > enable),
> > too many null packet will be inserted for cbr output.
> >
> > Please test with below command, you'll get huge test.ts without the patch:
> > ./ffmpeg -y -copyts -i ../fate-suite/mpegts/loewe.ts -c:v libx264
> > -x264opts \
> > nal-hrd=cbr:force-cfr=1 -b:v 3500k -minrate 3500k -maxrate 3500k
> > -bufsize \
> > 1000k -c:a mp2 -muxrate 4500k -vframes 1000 test.ts
> >
> > Signed-off-by: Limin Wang <lance.lmw...@gmail.com>
> > ---
> > libavformat/mpegtsenc.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> > index e05d0ce..baea3b4 100644
> > --- a/libavformat/mpegtsenc.c
> > +++ b/libavformat/mpegtsenc.c
> > @@ -81,6 +81,7 @@ typedef struct MpegTSWrite {
> > int64_t pat_period; /* PAT/PMT period in PCR time base */
> > int nb_services;
> > int64_t first_pcr;
> > + int first_dts_check;
> > int64_t next_pcr;
> > int mux_rate; ///< set to 1 when VBR
> > int pes_payload_size;
> > @@ -1136,6 +1137,7 @@ static int mpegts_init(AVFormatContext *s)
> >
> > if (ts->copyts < 1)
> > ts->first_pcr = av_rescale(s->max_delay, PCR_TIME_BASE,
> > AV_TIME_BASE);
> > + ts->first_dts_check = 1;
> >
> > select_pcr_streams(s);
> >
> > @@ -1690,6 +1692,11 @@ static int
> > mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
> > stream_id = side_data[0];
> >
> > if (ts->copyts < 1) {
> > + if (ts->first_dts_check && dts != AV_NOPTS_VALUE) {
> > + ts->first_pcr += dts * 300;
> > + }
> > + ts->first_dts_check = 0;
> > +
>
> Shouldn't the line "ts->first_dts_check = 0;" be inside the if()
> statement? Otherwise if the very first packet has a DTS of
> AV_NOPTS_VALUE then the first_pcr will never get incremented by the
> dts (since after the first run the check for first_dts_check will
> always fail).
Yes, you're right, will fix it.
>
> FWIW, the basic change is definitely useful, as I've had a nearly
> identical patch in my tree for some time:
>
> https://github.com/LTNGlobal-opensource/FFmpeg-ltn/commit/b974e431f7de39401a04d2c6e9bbdcc21e2982da
>
make fate will fail if I set first_pcr to AV_NOPTS_VALUE and add later like
your changes. So I add extra flag for the check.
> Devin
>
> --
> Devin Heitmueller, Senior Software Engineer
> LTN Global Communications
> o: +1 (301) 363-1001
> w: https://ltnglobal.com e: devin.heitmuel...@ltnglobal.com
--
Thanks,
Limin Wang
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